Rotary percussion drilling apparatus

ABSTRACT

This disclosure relates to apparatus for roof drilling in mines comprising a drill bit and hollow drill steel. The drill steel has apertures in its wall near the bit for the evacuation through the drill steel of rock dust. The bit has a plurality of cutting elements separated by plane channels which diverge rearwardly along the bit head to conduct cuttings and rock dust past the bit to the apertures in the drill steel.

United States Patent Inventor Harley G. Pyle Falrmont, W. Va.

App1.No. 819,811

Filed Apr. 28, 1969 Patented July 13, 1971 Assignee A. M. Byers Company Allhrldge, Pl.

ROTARY PERCUSSION DRILLING APPARATUS 9 Claims, 4 Drawing Figs.

11.8. C1. 175/410, 175/414 Int. CL E21: 13/08 Field 0| Search 175/213. 320,327,410, 412, 413,414 415,420

Relerenees Cited UNITED STATES PATENTS 5/1865 Smith 175/414 2,002,388 Bannister 175/413 X 2,252.745 8/1941 Williams 175/410 X 3,089,552 5/1963 Black et a1... 175/410X 3.163244 12/1964 Zimmerman 175/410 X 3,187,825 6/1965 Bower 175/327 3,434,554 3/1969 Bower 175/410 Primary Examiner-David H. Brown Attorney- Stanley .1. Price, Jr.

ABSTRACT: This disclosure relates to apparatus for roof drilling in mines comprising a drill bit and hollow drill steel. The drill steel has apertures in its wall near the bit for the evacuation through the drill steel of rock dust. The bit has a plurality of cutting elements separated by plane channels which diverge rearwardly along the bit head to conduct cuttings and rock dust past the bit to the apertures in the drill steel.

PATENTED JUL] 3 ml INVENTOR HARLEY 6. PYLES f.) 5 J A..

In: Altar/My ROTARY PERCUSSION DRILLING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to rock-drilling apparatus and more particularly to drill bits and drill steel for use in rotary percus sion drilling of mine roofs. Conventional apparatus for roof drilling generally comprises hollow drill steel connected at its lower end to a power source and to a vacuum device. The upper end of the drill steel is connected to a hollow drill bit which disintegrates the rock and permits evacuation of rock dust through the bit and drill steel.

Several problems are encountered with conventional drilling apparatus. The passage through the bit is frequently plugged by rock dust and cuttings. (The term, rock dust," is used herein to connote rock dust, cuttings, and all other types of material produced by action of the bit on the rocks.) With some types of conventional apparatus, the absence of cutting means near the center of the bit causes the formation ofa rock core which plugs the passage through the drill bit. Other conventional bits have cutting elements extending through the center of the bit, but such devices are inefficient because. at the center or midpoint of the bit, the velocity and displacement of the cutting element is minimal or zero, resulting in slow, ineffective grinding of the rocks and inhibition of the drilling action of other portions of the cutting elements on the bit.

One type of conventional drilling apparatus proposed to solve that problem provides for the evacuation of rock dust around the bit into the upper end of the drill steel. That apparatus has several disadvantages. One disadvantage is that the size of the opening for evacuating the rock dust is restricted by the means employed to connect the bit to the upper end of the drill steel. Another disadvantage inherent in such apparatus is that the conduit for evacuation of rock dust is removed from the immediate area of drilling and there is no provision made for transport of the cutting and rock dust from the drilling face to the evacuation conduit. Therefore, rock dust accumulates at the drilling face, causing a substantial loss in drilling efficiency and a hazardous working environment.

Another apparatus proposed to resolve the problems inherent in conventional roof drilling apparatus provides a cutting element which protrudes centrally into the drill bit just below the opening to the evacuation conduit through the bit. The obvious disadvantage in such apparatus is the restriction of the entry into the evacuation conduit with the increased likelihood of plugging.

2. Description ofthe Prior Art An example of the above-described earlier or conventional construction is in U.S. Pat. No. 2,597,30l to Curtis, issued May 20, 1952, which discloses hollow drill steel connected to a hollow drill bit having a plurality of cutting and chopping elements. U.S. Pat. No. 2,604,305 to Livingstone, issued July 22, 1952, discloses a cutting element projecting inwardly toward the center of the bit below the central opening through the bit. U.S. Pat. No. 3,032,]29 to Fletcher et al., issued, May 1, i962 discloses the combination ofa solid drill bit connected to hollow drill steel with rock dust removed around the bit and into the open end of the drill steel contiguous to the bit. U.S. Pat. No. 3,187,825 to Bower, issued June 8, I965, discloses the combination of a solid drill bit with hollow drill steel having side ports for removal of rock dust.

SUMMARY OF THE INVENTION In the present invention, a solid drill bit is connected to hollow drill steel having apertures extending through the wall thereof at the end of the drill steel near the bit. A plurality of cutting elements extend from the bit, and adjacent pairs of cutting elements are separated by one ofa plurality of inclined plane channels adapted to conduct rock dust away from the drilling face rearwardly of the bit toward the apertures in the drill steel.

In a preferred embodiment of this invention, each inclined plane channel is aligned with one of the apertures in the drill steel. In another preferred embodiment of this invention, the base surfaces of the plane channels converge toward the front of the bit to form an apex located within and among the plurality of cutting elements on the bit.

Each cutting element on the bit comprises a chuck integral with the head of the bit and adapted to engage and secure a cutting insert. The cutting elements are spaced nonradially around the head of the drill bit in such manner that the centerline through each cutting element is laterally displaced from the midpoint of the head of the bit.

The apparatus of this invention overcomes many of the disadvantages inherent in the prior types of apparatus. The solid drill bit provides greater structural strength and does not permit plugging of the entry to the evacuation conduit by a rock core or dust. The presence of a plurality of cutting elements which do not extend into the center of the drill head restricts the cutting and grinding action of the cutting elements to those areas of the drilling face where the cutting and grinding action are most efficient and avoids the inefficient, slow grinding of a central core where the velocity and displacement of the cutting element are equal, or nearly equal, to zero.

The apex formed by intersection of the plane channels in the midst of the cutting elements provides a means to chip and fragment the central rock core under the percussive action of the drill. Because all surfaces of the drill bit contiguous or adjacent to the drilling face are steeply sloping away from the drilling face, the surface area of the drill bit available to permit the accumulation of rock dust is minimized and the rock dust is conducted rapidly away from the drilling face and guided by the plane channels toward the apertures in the drill steel for removal from the working area.

The plurality of lateral apertures in the drill steel permit a greater rate of flow of rock dust and air into the drill steel and also provide a means for intercepting whatever portion of the rock dust would otherwise escape collection by falling downwardly along the lateral surfaces of the bit and drill steel.

It is an object of this invention to provide a. rotary percussion rock drilling bit having solid construction for greater strength and a plurality ofseparate, nonradially spaced cutting elements providing greater speed and efficiency in drilling.

It is another object of this invention to provide a drill bit adapted to effect rapid and substantially total removal of rock dust from the drilling face.

It is a further object of this invention to provide a combination drill bit and drill steel adapted to remove rock dust rapidly from the drilling face and adapted to evacuate substantially all the rock dust more rapidly and more efficiently than was heretofore possible.

DESCRIPTION OF THE DRAWINGS This invention can be more clearly understood from the following description with reference to the accompanying drawings in which:

FIG. 1 is a perspective view showing the combination of the drill bit of this invention connected to the upper end of the hollow drill steel.

FIG. 2 is a top plan view of the drill bit of this invention.

FIG. 3 is a side elevation of the drill bit.

FIG. 4 is another side elevation of the drill bit corresponding in the orientation of parts to the top plan view of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and in particular to FIG. 1, there is illustrated the rotary percussion drilling apparatus of this in vention comprising hollow drill steel [0 having formed, near one end thereof, a plurality of apertures l2 extending through the wall ofdrill steel 10 and permitting the passage of air and other materials through apertures 12 into the longitudinal opening (not shown) through drill steel I0.

The size, shape and number of apertures 12 in drill steel are not critical aspects of this invention; however, in a preferred embodiment of this invention, apertures 12 are elongated parallel to the longitudinal axis of drill steel 10 while assuring substantial strength in drill steel 10 in the area close to the drilling face.

In another preferred embodiment of this invention, the number of apertures in drill steel 10 should be at least equal to the number of plane channels present on the head of the drill bit. The structure of the drill bit and the interaction of the plane channels with apertures 12 will be explained more fully below.

One end. 14, of drill steel 10 engages, and abuts against, the rear surface of a drill bit 20, as shown in FIG. 1. End 14 in drill steel 10 has an opening therethrough adapted to engage the shank 24 of drill bit 20, described below. The structure of the opening in end 14 is not critical to this invention and is not shown in the drawings.

Between apertures 12 and end 14, drill steel 10 has a pair of holes 16 extending through opposite sides thereof and coaxially aligned with each other. Holes 16 are adapted for align ment with similar holes in the shank 24 of bit 20 and are adapted to receive a pin 18, or other suitable connecting means, which passes through the holes 16 and the holes in shank 24 of bit 20, thereby securing the bit in drill steel 10.

Drill bit 20 comprises a head 22 and a shank 24 integral with head 22 and extending rearwardly thereof. Shank 24 may be of any cross-sectional configuration suitable for engagement with the opening in end 14 of drill steel 10. Shank 24 has extending therethrough a hole 26 adapted for alignment with holes 16 in drill steel 10 and adapted to receive the pin [8, or other suitable connecting means.

Bit head 22 comprises a face 28 and a plurality of cutting means 30 integral with face 28 and extending forwardly beyond the surface of the face 28. Each cutting means 30 comprises a chuck 32 integral with bit face 28 at the base of chuck 32 and having a slot 34 formed through the top of chuck 32 remote from bit face 28. Each cutting means 30 also comprises a cutting insert 36 secured in slot 34 of chuck 32. Cutting insert 36 may be constructed of any conventional hard. wear resistant material such as tungsten carbide or the like. Cutting insert 36 is constructed to form a knife edge 38 adapted to disintegrate rock at the drilling face by cutting. chipping, grinding, and the like. Cutting insert 36 can be secured in slot 34 of chuck 32 by any suitable means. It is preferred that cutting insert 36 be secured in chuck 32 by some means permitting removal and replacement of cutting insert 36 when necessary. As thus far described, the form and construction of cutting means 30 are not critical to this invention, and any conventional or other suitable means can be employed.

The face 28 of bit head 22 is formed by a plurality of intersecting inclined planes which diverge rearwardly from the longitudinal axis of the bit 20. Those inclined planes are illustrated in the drawings, and in particular in FIG. 2, by the reference numerals 40, 42 and 44. Each of the cutting means 30, although integral with face 28 of head 22, is so constructed and arranged that no part of the cutting means 30 extends into the central area of face 28. in the central area of face 28, inclined planes 40, 42 and 44 intersect mutually to form a structural apex 46. Apex 46 functions as an additional rockdisintegrating means for cutting. chipping and grinding rock segments not disintegrated by the cutting means 30. The function of apex 46 is more fully described below. Apex 46, and inclined planes 40, 42 and 44, can be constructed of any material having hardness and durability suitabie for use in rock drilling.

The structures described above and shown in the drawings comprise preferred embodiments of this invention. Also within the scope of this invention are alternative structures such as the intersection of the inclined planes of bit face 28 to form a knife edge or to form a plurality of apexes or knife edges. A structure adapted to provide any such cutting means or other equivalent within the central area of bit face 28 is comprehended by this invention.

Although three separate cutting means 3|] are shown in the drawings, more or less cutting means can be provided without departing from the scope of this invention. Inspection of FIG. 2 will illustrate one unique aspect of the present invention. Each cutting means 30 is located and arranged nonradially on face 28 of bit head 22 in such manner that the longitudinal axis passing through cutting means 30 is laterally displaced from the midpoint of bit face 28. That construction imparts greater strength to bit 20 by distributing more uniformly over a wider area the stresses imposed in operation.

Another possible alternative structural feature of the present invention is the provision of cutting means 30 of unequal lengths. That is, each cutting means 30 extends inwardly along drill head 22 from the periphery of head 22 for a distance different from that of the other cutting elements 30. The operation of that element of structure is described more fully below.

The structural combination of the inclined planes 40, 42 and 44 with a plurality of cutting means 30 defines a plurality of channels 48,50 and 52, which diverge from the central area of bit face 28 at apex 46 rearwardly along head 22 to the edge thereof adjacent end 14 ofdrill steel 10.

In operation, the drill bit structure disclosed in this inven tion offers many advantages over structures available heretofore. The drill bit of this invention provides solid construction for greater strength and durability. The absence of a central opening through the bit prevents the problem of plugging the rock dust evacuation conduit which is present with other types of bits. A rock core which might tend to protrude into the region of bit face 28 centrally located among the cutting means 30 is chipped and broken both by the percussive and compressive action of apex 46 and by the torsional and lateral cutting stresses applied to such rock core by impact with the inner corners of chucks 32.

The drilling bit disclosed in this invention can be used for rotary drilling, or for percussive drilling, or for a combination of rotary percussion drilling. The rock surface off setting the center area of the drill bit is more rapidly disintegrated using the apparatus of this invention by the action of apex 46 under percussive and compressive impact and by the action of the chucks 32 under torsional impact during rotation. Thus the slow, inefficient process of rock disintegration by grinding is replaced by the more rapid and highly efficient combination of compressive percussive impact and torsional lateral impact imparted by the apparatus of this invention.

Another advantage in the structure of the drilling apparatus disclosed herein is found in the adaptation of the bit structure for rapid and total removal of rock dust from the drilling face. The drilling bit of this invention provides little or no surface area oriented transverse to the direction of advance of the bit. All of the surfaces of the bit and drilling means contiguous or adjacent to the bit are vertical or inclined downwardly away from the drilling face and are adapted to conduct and transport rock dust downwardly through channels 48, 50, and S2 to apertures 12 in drill steel 10. In a preferred embodiment of this invention, drill bit 20 is secured in drill steel 10 with each channel 48, 50 and 52 aligned with an aperture 12 in drill steel 10.

In operation, the combination of the drill bit and drill steel disclosed in this invention provide structure permitting evacuation into the drill steel of a large volume of air and rock dust through the plurality of apertures in the drill steel. Plugging of the apertures is avoided, and optimum use of the aperture area is afforded by rapid conduction of rock dust away from the drilling face through the channels 48, S0 and 52, downwardly along the drill steel to the apertures 12.

In addition to the several embodiments described herein, it should be understood that various modifications and variations of this disclosure might be effected without departing from the concept and scope ofthe invention disclosed herein.

lclaim:

I. Drilling apparatus comprising:

drill steel having a longitudinal passage extending therethrough and having a plurality of apertures extending through the side thereof and communicating with said longitudinal passage near one end of said drill steel;

a drill bit connected to one end of the drill steel;

said drill bit having a face remote from the drill steel;

said drill bit having a plurality of cutting means spaced around the face thereof;

said face comprising a plurality of inclined planes;

each of said inclined planes extending between a pair of adjacent cutting means rearwardly along said drill bit toward said drill steel.

2. A drilling apparatus as described in claim 1 wherein said inclined planes diverge rearwardly toward said drill steel from an apex located among said cutting means.

3. Drilling apparatus as described in claim 1 wherein each of said inclined planes extends rearwardly toward said drill steel in alignment with one of said apertures.

4. Drilling apparatus as described in claim 1 having three separate cutting means with each pair of adjacent cutting means separated by an inclined plane.

5. Drilling apparatus as described in claim I wherein each of said cutting means comprises:

a chuck integral with the drill face and extending forwardly therefrom;

a cutting insert; and

means in said chuck adapted to engage and secure said cutting insert.

6. Drilling apparatus as described in claim 5 wherein each chuck is positioned nonradially on the drill face with the centerline of the chuck laterally displaced from the midpoint of the drill face.

7. A drill bit comprising;

a drill face;

a plurality of separate cutting elements integral with said drill face;

each of said cutting elements positioned nonradially on said drill face with the centerline of said cutting elements laterally displaced from the midpoint of said drill face;

each of said cutting elements having inner end portions terminating at a location spaced radially outwardly from the midpoint of said drill face;

a plurality of inclined planes extending rearwardly along said drill face from an apex located at the axial center of said drill bit;

each of said inclined planes extending from the midpoint of said drill face. said inclined planes each forming a rearwardly sloped channel and separating a pair of adjacent cutting elements.

8. A drill bit as described in claim 7 in which:

said plurality of separate cutting elements consists of three separate cutting elements spaced around the drill face; and

each pair of adjacent separate cutting elements separated by a rearwardly extending inclined plane.

9. A drill bit as described in claim 7 wherein each cutting element includes;

a chuck integral with the bit face;

a cutting insert; and

engaging means in said chuck to engage and secure said cutting insert to said chuck. 

1. Drilling apparatus comprising: drill steel having a longitudinal passage extending therethrough and having a plurality of apertures extending through the side thereof and communicating with said longitudinal passage near one end of said drill steel; a drill bit connected to one end of the drill steel; said drill bit having a face remote from the drill steel; said drill bit having a plurality of cutting means spaced around the face thereof; said face comprising a plurality of inclined planes; each of said inclined planes extending between a pair of adjacent cutting means rearwardly along said drill bit toward said drill steel.
 2. A drilling apparatus as described in claim 1 wherein said inclined planes diverge rearwardly toward said drill steel from an apex located among said cutting means.
 3. Drilling apparatus as described in claim 1 wherein each of said inclined planes extends rearwardly toward said drill steel in alignment with one of said apertures.
 4. Drilling apparatus as described in claim 1 having three separate cutting means with each pair of adjacent cutting means separated by an inclined plane.
 5. Drilling apparatus as described in claim 1 wherein each of said cutting means comprises: a chuck integral with the drill face and extending forwardly therefrom; a cutting insert; and means in said chuck adapted to engage and secure said cutting insert.
 6. Drilling apparatus as described in claim 5 wherein each chuck is positioned nonradially on the drill face with the centerline of the chuck laterally displaced from the midpoint of the drill face.
 7. A drill bit comprising; a drill face; a plurality of separate cutting elements integral with said drill face; each of said cutting elements positioned nonradially on said drill face with the centerline of said cutting elements laterally displaced from the midpoint of said drill face; each of said cutting elements having inner end portions terminating at a location spaced radially outwardly from the midpoint of said drill face; a plurality of inclined planes extending rearwardly along said drill face from an apex located at the axial center of said drill bit; each of said inclined planes extending from the midpoint of said drill face, said inclined planes each forming a rearwardly sloped channel and separating a pair of adjacent cutting elements.
 8. A drill bit as described in claim 7 in which: said plurality of separate cutting elements consists of three separate cutting elements spaced around the drill face; and each pair of adjacent separate cutting elements separated by a rearwardly extending inclined plane.
 9. A drill bit as described in claim 7 wherein each cutting element includes; a chuck integral with the bit face; a cutting insert; and engaging means in said chuck to engage and secure said cutting insert to said chuck. 